Technical Abstract:
Phytochemicals, microbial metabolites, and agrochemicals can individually or collectively impact the diversity and frequency of fungal species occurring in agricultural field environments. Resistance to such chemicals by plant pathogenic fungi is common and potentially devastating to crop quality, yield, and value because those fungi may ultimately dominate the overall fungal community. Fusarium verticillioides (Gibberella moniliformis) is such a fungus commonly associated with corn worldwide and is of great concern due to the ear rot it causes and contamination of corn kernels with the fumonisin mycotoxins. The dominance of F. verticillioides in corn field environments may be due in part to its ability to metabolize phytoprotectants produced by corn. The benzoxazinoids and benzoxazolinones are broad spectrum allelopathic, antimicrobial, and anti-herbivory compounds, yet F. verticillioides can rapidly biotransform these corn phytochemicals into non-toxic malonamic acid metabolites. To better understand the genetics and chemistry of this metabolic process, genomic tools were utilized to identify genes essential for the biotransformation activity. Genes within two clusters conferred metabolic tolerance to 2-benzoxazolinone (BOA). One such gene encoded an arylamine N-acetyltransferase (NAT), a gene family not previously characterized in filamentous fungi. Further analysis of this NAT and additional gene products may provide insight into novel metabolic resistance mechanisms exhibited by fungi to a range of azole and arylamine compounds, including common fungicides. The impact of such mechanisms on community dynamics can also be evaluated.